Network entity, user equipment and method for the control and use of network slices

ABSTRACT

A network entity is proposed for controlling the use, by a user equipment, of network slices of a communication network comprising a plurality of slice support areas. Each slice support area comprises at least one cell, and all cells of a given slice support area support the same network slices. A registration area for the registration of the user equipment with the communication network comprises at least one slice support area. The network entity is adapted to transmit, to the user equipment, slice support information for at least one slice support area of the communication network. The slice support information for a given slice support area indicates at least one network slice supported by the given slice support area and/or at least one network slice not supported by the given slice support area.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/810,583, filed on Mar. 5, 2020, which is a continuation ofInternational Application No. PCT/EP2017/072189, filed on Sep. 5, 2017.All of the afore-mentioned patent applications are hereby incorporatedby reference in their entireties.

TECHNICAL FIELD

The present invention generally relates to the field of communicationnetwork technology. Particularly, the present invention relates to anetwork entity for controlling the use of network slices by a userequipment, and to a user equipment, UE, for using network slices.

BACKGROUND

The concept of network slice or network slicing is introduced in fifthgeneration, 5G, communication systems in order to address the variousrequirements from multiple vertical industries assuming a shared networkinfrastructure. Correspondingly, network services can be customizedbased on the requirements of different use cases, thereby increasing thenetwork operation efficiency.

Similarly to the structure of a Long Term Evolution, LTE, system or aUniversal Mobile Telecommunications System, UMTS, system, the network ofa 5G communication system comprises a Radio Access Network, RAN, and aCore Network, CN. In order to obtain service connectivity and e.g. inorder to access a service corresponding to a network slice in a 5Gcommunication system, the UE attaches to the CN through the RAN.

Once a communication link is established between the UE and the network,and particularly between the UE and the CN, the service of network slicecan be accessed by the UE. In the presence of such a communication linkbetween the UE and the CN through the RAN, the UE is in a state/modethat is generally referred to as connected state or active state. Whenthe UE no longer uses the service of a network slice, that UE may removeor stop the communication link between the UE and the network. The stateof the UE is then generally referred to as idle state.

When a UE is in idle state, i.e. when the UE is not actively engaged ina communication, the network—generally the CN—keeps track of thelocation of the UE with the accuracy of a defined area in the system.Such a defined area is known e.g. from LTE, UMTS, and GSM (Global Systemfor Mobile Communications) systems. In UMTS, such a defined area isreferred to as a location area or a routing area. In an LTE system, sucha defined area is generally referred to as a Tracking Area, TA, whereina TA can comprise one or a plurality of cells. A TA is identified by aTracking Area identity, TAI. Thereby, the UE is registered in a specificarea consisting of at least one TA, identified by a list of TAI. Whenthe UE leaves this specific area the UE registers in another area.

In 5G systems, the UE can be registered in one or more TAs, wherein saidone or more TAs define a Registration Area, RA. In other words, the RAis a TAI list. Consequently, a registration at RA-level allows for morethan one TA to be assigned to a UE through a single procedure. As longas the UE roams within the TAs that are comprised in the registered RA,the UE does not need to perform a new registration procedure.

Due to diverse deployment and dynamic situations (e.g., load, resource,physical capabilities of the wireless access nodes) in 5G RAN, somenetwork slices may be available only in part of the network. Sliceavailability can also depend on the operator deployment and differentnetwork deployments pertaining to different operators can have differentlevels of slice support.

When a UE moves, it may go to an area where it registered slice in thenetwork is not supported anymore or where some new network slice(s)could be supported. Therefore, the UE needs to be aware of the change ofsupported network slice(s). It is disadvantageous that the UE asks forthe service of unsupported network slices, which implies cost signallingoverhead and latency. It is furthermore disadvantageous that the UEmisses new slices that could be provided by the network at certainlocation.

SUMMARY

Having recognized the above-mentioned disadvantages and problems, thepresent invention aims to improve the state of the art. In particular,an object of the present invention is to provide a network entity, auser equipment and methods for improving the user equipment awareness ofthe network slice support.

The above-mentioned object is achieved by the features of theindependent claims. Further embodiments of the invention are apparentfrom the dependent claims, the description and the figures.

According to a first aspect, the invention relates to a network entityfor controlling the use, by a user equipment, of network slices of acommunication network comprising a plurality of slice support areas.Each slice support area comprises at least one cell, and all cells of agiven slice support area support the same network slices. A registrationarea for the registration of the user equipment with the communicationnetwork comprises at least one slice support area. The network entity isadapted to transmit, to the user equipment, slice support informationfor at least one slice support area of the communication network. Theslice support information for a given slice support area indicates atleast one network slice supported by the given slice support area and/orat least one network slice not supported by the given slice supportarea.

Thereby, the user equipment awareness of the slice support can beimproved. The improved slice awareness has the advantage that the userequipment has an improved knowledge of the change of supported networkslices within the communication network. This in turn has the furtheradvantage that the user equipment will not ask for the service ofunsupported slices, which reduces the cost signalling overhead and thelatency period. A further advantage is that the user equipment will notmiss any network slices that could be provided by the communicationnetwork in certain slice support areas.

According to a first implementation of the network entity according tothe first aspect, the network entity is adapted to allocate aregistration area to the user equipment for the registration of the userequipment with the communication network. The network entity is furtheradapted to transmit, to the user equipment, slice support informationfor all or a part of the slice support areas of the registration area.

Thereby, the transmission of slice support information for slice supportareas of the registration area specifically improves the user equipmentawareness of the slice support within the registration area. This isadvantageous because the user equipment experience can be improved incase of heterogeneous radio access network (RAN) slice deployment.Furthermore, this facilitates the design of registration area in thenetwork: e.g. it is possible to define a larger registration area withheterogonous slice support in the registration area, and at the sametime the frequency and signalling overhead for a registration areaupdate can be reduced because the registration area is larger. This inturn improves the system efficiency because less control signalling isrequired between the user equipment and the network.

According to a second implementation of the network entity according tothe first aspect, the network entity is adapted to transmit the slicesupport information and registration area information in a message tothe user equipment. The registration area information indicates the atleast one slice support area comprised in the registration area.

Thereby, the registration area information and the slice supportinformation can be transmitted to the user equipment in one singlemessage. Such a single message transmission is advantageous in that noadditional message is required for transmitting the slice supportinformation. Accordingly, the signalling overhead can be reduced.

According to a third implementation of the network entity according tothe first aspect, the network entity is adapted to transmit the slicesupport information in a Non-Access Stratum, NAS, message over asignalling interface defined between the network entity and the userequipment.

Thereby, the slice support information can be transmitted to the userequipment even if no data communication link is established between theuser equipment and the communication network.

According to a fourth implementation of the network entity according tothe first aspect, the network entity is adapted to transmit the slicesupport information to the user equipment during a procedure ofregistration of the user equipment with the communication network,particularly during an initial registration procedure or during aregistration update procedure.

Thereby, the slice support information can be transmitted to the userequipment together with other information transmitted to the userequipment during a registration procedure. It is thereforeadvantageously not necessary to transmit the slice support informationby means of a new additional procedure. Furthermore, the transmission ofthe slice support information can be easily integrated in a Registrationprocedure of a 5G communication network.

According to a fifth implementation of the network entity according tothe first aspect, the network entity is adapted to transmit the slicesupport information to the user equipment during a user equipmentconfiguration update procedure. The user equipment configuration updateprocedure is particularly used when the network entity wants to changethe user equipment configuration or wants to trigger a user equipmentregistration update procedure.

Thereby, the slice support information can be transmitted to the userequipment together with other information transmitted to the userequipment during a user equipment configuration update procedure. It istherefore advantageously not necessary to transmit the slice supportinformation by means of a new additional procedure. Furthermore, thetransmission of the slice support information can be easily integratedin a UE Configuration Update procedure of a 5G communication network.

According to a sixth implementation of the network entity according tothe first aspect, a network slice is identified by a Single NetworkSlice Selection Assistance information, S-NSSAI. The slice supportinformation for a given slice support area comprises the S-NSSAI of atleast one network slice supported or not supported by the given slicesupport area.

Thereby, user equipment awareness of the slide support can be increasedby transmitting only a small amount of information. With a small amountof high-level signalling information transmitted from the network to theuser equipment, the user equipment experience can be improved withoutscarifying the system efficiency.

According to a seventh implementation of the network entity according tothe first aspect, a slice support area is a Tracking Area and isidentified by a Tracking Area identity, TAI. A TAI list comprises theTAI of each Tracking Area comprised in the registration area. Thenetwork entity is adapted to associate, to each given TAI of the TAIlist, an S-NSSAI list comprising the S-NSSAI of at least one networkslice supported or not supported by the Tracking Area identified by thegiven TAI. The network entity is adapted to transmit, to the userequipment, the TAI list and the respective S-NSSAI list associated toeach TAI of the TAI list.

Thereby, the user equipment awareness of the slice support can beimproved in an efficient way by transmitting a compact amount ofinformation.

According to an eighth implementation of the network entity according tothe first aspect, the network entity is adapted to allocate aregistration area to the user equipment for the registration of the userequipment with the communication network. The registration areacomprises at least one slice support area of the communication network.The network entity is adapted to transmit, to the user equipment, slicesupport information for at least one slice support area that is notcomprised in the registration area. Alternatively or in additionthereto, the network entity is adapted to transmit to the user equipmentslice support information for at least one slice support area that isneighbouring a slice support area of the registration area.

Thereby, the slice awareness of the user equipment is improved withregard to slice support areas outside of the registration area. This isadvantageous in that the user equipment can already analyse the networkslices that are supported outside of the registration area. In case theregistration area is updated by the communication network, for examplebecause the user equipment leaves the registration area, the userequipment can more rapidly use the supported network slices. Indeed, theuser equipment does not need to wait for the reception of slice supportinformation regarding the new registration area.

According to a ninth implementation of the network entity according tothe first aspect, the network entity is adapted to select the at leastone slice support area of the registration area for the registration ofthe user equipment with the communication network. The at least oneslice support area is selected based on a state and/or a profile and/ora capability of the user equipment.

Thereby, the network entity can optimize the design of the registrationarea that the network allocates to the user equipment. The state of theuser equipment can be idle state or active or connected state. Theprofile of the user equipment can define which network slices the userequipment is allowed to connect to. The capability of the user equipmentcan define its physical capability or capabilities.

According to a tenth implementation of the network entity according tothe first aspect, the network entity is adapted to select the at leastone network slice indicated by the slice support information based on astate of the user equipment and/or a profile of the user equipmentand/or a capability of the user equipment and/or use information. Theslice use information indicates which network slice(s) can be used bythe user equipment or which network slice(s) the user equipment isallowed to use.

Thereby, the network entity can optimize the transmitted slice supportinformation. The state of the user equipment can be idle state or activeor connected state. The profile of the user equipment can define whichnetwork slices the user equipment is allowed to connect to. Thecapability of the user equipment can define its physical capability orcapabilities. The slice use information can for example be received fromthe user equipment, or can be alternatively stored in the communicationnetwork, particularly in the network entity itself

According to an eleventh implementation of the network entity accordingto the first aspect, the network entity implements an Access andMobility Management function, AMF.

Thereby, the network entity can be used in a 5G communication network,since the Access and Mobility Management function is a network functionof a 5G communication network.

According to a second aspect, the invention relates to a method forcontrolling the use of network slices by a user equipment in acommunication network comprising a plurality of slice support areas.Each slice support area comprises at least one cell, and all cells of agiven slice support area support the same network slices. A registrationarea for the registration of the user equipment with the communicationnetwork comprises at least one slice support area. The method comprisestransmitting, to the user equipment, slice support information for atleast one slice support area of the communication network. The slicesupport information for a given slice support area indicates at leastone network slice supported by the given slice support area and/or atleast one network slice not supported by the given slice support area.

Thereby, the user equipment awareness of the slice support can beimproved. The improved slice awareness has the advantage that the userequipment has an improved knowledge of the change of supported networkslices within the communication network. This in turn has the furtheradvantage that the user equipment will not ask for the service ofunsupported slices, which reduces the cost signalling overhead and thelatency period. A further advantage is that the user equipment will notmiss any network slices that could be provided by the communicationnetwork in certain slice support areas.

According to a first implementation of the method according to thesecond aspect, the method comprises allocating a registration area tothe user equipment for the registration of the user equipment with thecommunication network. The method further comprises transmitting, to theuser equipment, slice support information for all or a part of the slicesupport areas of the registration area.

Thereby, the transmission of slice support information for slice supportareas of the registration area specifically improves the user equipmentawareness of the slice support within the registration area. This isadvantageous because the user equipment experience can be improved incase of heterogeneous radio access network (RAN) slice deployment.Furthermore, this facilitates the design of registration area in thenetwork: e.g. it is possible to define a larger registration area withheterogonous slice support in the registration area, and at the sametime the frequency and signalling overhead for a registration areaupdate can be reduced because the registration area is larger. This inturn improves the system efficiency because less control signalling isrequired between the user equipment and the network.

According to a second implementation of the method according to thesecond aspect, the method comprises transmitting the slice supportinformation and registration area information in a message to the userequipment. The registration area information indicates the at least oneslice support area comprised in the registration area.

Thereby, the registration area information and the slice supportinformation can be transmitted to the user equipment in one singlemessage. Such a single message transmission is advantageous in that noadditional message is required for transmitting the slice supportinformation. Accordingly, the signalling overhead can be reduced.

According to a third implementation of the method according to thesecond aspect, the method comprises transmitting the slice supportinformation in a Non-Access Stratum, NAS, message over a signallinginterface defined between the communication network and the userequipment.

Thereby, the slice support information can be transmitted to the userequipment even if no data communication link is established between theuser equipment and the communication network.

According to a fourth implementation of the method according to thesecond aspect, the method comprises transmitting the slice supportinformation to the user equipment during a procedure of registration ofthe user equipment with the communication network, particularly duringan initial registration procedure or during a registration updateprocedure.

Thereby, the slice support information can be transmitted to the userequipment together with other information transmitted to the userequipment during a registration procedure. It is thereforeadvantageously not necessary to transmit the slice support informationby means of a new additional procedure. Furthermore, the transmission ofthe slice support information can be easily integrated in a Registrationprocedure of a 5G communication network.

According to a fifth implementation of the method according to thesecond aspect, the method comprises transmitting the slice supportinformation to the user equipment during a user equipment configurationupdate procedure. The user equipment configuration update procedure isparticularly used when the communication network wants to change theuser equipment configuration or wants to trigger a user equipmentregistration update procedure.

Thereby, the slice support information can be transmitted to the userequipment together with other information transmitted to the userequipment during a user equipment configuration update procedure. It istherefore advantageously not necessary to transmit the slice supportinformation by means of a new additional procedure. Furthermore, thetransmission of the slice support information can be easily integratedin a UE Configuration Update procedure of a 5G communication network.

According to a sixth implementation of the method according to thesecond aspect, a network slice is identified by a Single Network SliceSelection Assistance information, S-NSSAI. The slice support informationfor a given slice support area comprises the S-NSSAI of at least onenetwork slice supported or not supported by the given slice supportarea.

Thereby, user equipment awareness of the slide support can be increasedby transmitting only a small amount of information. With a small amountof high-level signalling information transmitted from the network to theuser equipment, the user equipment experience can be improved withoutscarifying the system efficiency.

According to a seventh implementation of the method according to thesecond aspect, a slice support area is a Tracking Area and is identifiedby a Tracking Area identity, TAI. A TAI list comprises the TAI of eachTracking Area comprised in the registration area. The method comprisesassociating, to each given TAI of the TAI list, an S-NSSAI listcomprising the S-NSSAI of at least one network slice supported or notsupported by the Tracking Area identified by the given TAI. The methodcomprises transmitting, to the user equipment, the TAI list and therespective S-NSSAI list associated to each TAI of the TAI list.

Thereby, the user equipment awareness of the slice support can beimproved in an efficient way by transmitting a compact amount ofinformation.

According to an eighth implementation of the method according to thesecond aspect, the method comprises allocating a registration area tothe user equipment for the registration of the user equipment with thecommunication network. The registration area comprises at least oneslice support area of the communication network. The method comprisestransmitting, to the user equipment, slice support information for atleast one slice support area that is not comprised in the registrationarea. Alternatively or in addition thereto, the method comprisestransmitting, to the user equipment, slice support information for atleast one slice support area that is neighbouring a slice support areaof the registration area.

Thereby, the slice awareness of the user equipment is improved withregard to slice support areas outside of the registration area. This isadvantageous in that the user equipment can already analyse the networkslices that are supported outside of the registration area. In case theregistration area is updated by the communication network, for examplebecause the user equipment leaves the registration area, the userequipment can more rapidly use the supported network slices. Indeed, theuser equipment does not need to wait for the reception of slice supportinformation regarding the new registration area.

According to a ninth implementation of the method according to thesecond aspect, the method comprises selecting the at least one slicesupport area of the registration area for the registration of the userequipment with the communication network. The at least one slice supportarea is selected based on a state and/or a profile and/or a capabilityof the user equipment.

Thereby, the communication network can optimize the design of theregistration area that the network allocates to the user equipment.

According to a tenth implementation of the method according to thesecond aspect, the method comprises selecting the at least one networkslice indicated by the slice support information based on a state of theuser equipment and/or a profile of the user equipment and/or acapability of the user equipment and/or slice use information. The sliceuse information indicates which network slice(s) can be used by the userequipment or which network slice(s) the user equipment is allowed touse.

Thereby, the network entity can optimize the transmitted slice supportinformation. The state of the user equipment can be idle state or activeor connected state. The profile of the user equipment can define whichnetwork slices the user equipment is allowed to connect to. Thecapability of the user equipment can define its physical capability orcapabilities. The slice use information can for example be received fromthe user equipment, or can be alternatively stored in the communicationnetwork, particularly in the network entity itself

According to an eleventh implementation of the method according to thesecond aspect, the method comprises implementing an Access and MobilityManagement function, AMF.

Thereby, the method can be used in a 5G communication network, since theAccess and Mobility Management function is a network function of a 5Gcommunication network.

According to a third aspect, the invention relates to a communicationnetwork comprising at least one network entity according to the firstaspect.

According to a fourth aspect, the invention relates to a user equipmentfor using network slices of a communication network comprising aplurality of slice support areas. Each slice support area comprises atleast one cell, and all cells of a given slice support area support thesame network slices. A registration area for the registration of theuser equipment with the communication network comprises at least oneslice support area. The user equipment is adapted to receive, from thecommunication network, slice support information for at least one slicesupport area of the communication network. The slice support informationfor a given slice support area indicates at least one network slicesupported by the given slice support area and/or at least one networkslice not supported by the given slice support area.

Thereby, the user equipment awareness of the slice support can beimproved. The improved slice awareness has the advantage that the userequipment has an improved knowledge of the change of supported networkslices within the communication network. This in turn has the furtheradvantage that the user equipment will not ask for the service ofunsupported slices, which reduces the cost signalling overhead and thelatency period. A further advantage is that the user equipment will notmiss any network slices that could be provided by the communicationnetwork in certain slice support areas.

According to a first implementation of the user equipment according tothe fourth aspect, the user equipment is adapted to transmit a servicerequest to the communication network for a service corresponding to anetwork slice defined in the received slice support information.

Thereby, the user equipment can use the slice support information todecide on the network slice to be initiated by a service request.Advantageously, the user equipment can map the service request to anavailable network slice that is not a default or optimal network slicefor that service. Also, it is advantageous that the user equipment canmap the service request to the default/optimal network slice for thatservice only in case that network slice is available.

According to a fifth aspect, the invention relates to a method forusing, by a user equipment, network slices of a communication networkcomprising a plurality of slice support areas. Each slice support areacomprises at least one cell, and all cells of a given slice support areasupport the same network slices. A registration area for theregistration of the user equipment with the communication networkcomprises at least one slice support area. The method comprisesreceiving, from the communication network, slice support information forat least one slice support area of the communication network. The slicesupport information for a given slice support area indicates at leastone network slice supported by the given slice support area and/or atleast one network slice not supported by the given slice support area.

Thereby, the user equipment awareness of the slice support can beimproved. The improved slice awareness has the advantage that the userequipment has an improved knowledge of the change of supported networkslices within the communication network. This in turn has the furtheradvantage that the user equipment will not ask for the service ofunsupported slices, which reduces the cost signalling overhead and thelatency period. A further advantage is that the user equipment will notmiss any network slices that could be provided by the communicationnetwork in certain slice support areas.

According to a first implementation of the method according to the fifthaspect, the method comprises transmitting a service request to thecommunication network for a service corresponding to a network slicedefined in the received slice support information.

Thereby, the user equipment can use the slice support information todecide on the network slice to be initiated by a service request.Advantageously, the user equipment can map the service request to anavailable network slice that is not a default or optimal network slicefor that service. Also, it is advantageous that the user equipment canmap the service request to the default/optimal network slice for thatservice only in case that network slice is available.

According to a sixth aspect, the invention relates to computer programhaving a program code for performing the method according to the secondor fifth aspect, when the computer program runs on a computing device.

Thereby, the method can be performed in an automatic and repeatablemanner. Advantageously, the computer program can be respectivelyperformed by the network entity according to the first aspect or by theuser equipment according to the fourth aspect.

More specifically, it should be noted that the above apparatuses may beimplemented based on a discrete hardware circuitry with discretehardware components, integrated chips or arrangements of chip modules,or based on a signal processing device or chip controlled by a softwareroutine or program stored in a memory, written on a computer-readablemedium or downloaded from a network such as the internet.

It shall further be understood that a preferred embodiment of theinvention can also be any combination of the dependent claims or aboveembodiments with the respective independent claim.

These and other aspects of the invention will be apparent and elucidatedwith reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The above aspects and implementation forms of the present invention willbe explained in the following description of specific embodiments inrelation to the enclosed drawings, in which

FIG. 1 shows a system comprising a communication network and a userequipment according to an embodiment of the present invention,

FIG. 2 shows slice support information according to an embodiment of thepresent invention,

FIG. 3 shows a scenario with different slice supports according to anembodiment of the present invention,

FIG. 4 shows a transmission of slice support information during aregistration procedure according to an embodiment of the presentinvention, and

FIG. 5 shows a transmission of slice support information during a userequipment configuration update procedure according to an embodiment ofthe present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1 shows a system 100 comprising a communication network 104 and auser equipment, UE, 102 according to an embodiment of the presentinvention.

The communication network 104 comprises a network entity 114 forcontrolling the use, by the user equipment 102, of network slices of thecommunication network 104. The communication network 104 comprises aplurality of slice support areas. Each slice support area comprises atleast one cell, and all cells of a given slice support area support thesame network slices. A registration area, which is adapted to be usedfor the registration of the user equipment 102 with the communicationnetwork 104, comprises at least one slice support area.

The network entity 114 is adapted to transmit, to the user equipment102, slice support information 116 for at least one slice support areaof the communication network 104. The slice support information 116 fora given slice support area indicates at least one network slice that issupported by the given slice support area. Alternatively or in additionthereto, the slice support information 116 for a given slice supportarea indicates at least one network slice that is not supported by thegiven slice support area.

The user equipment 102 is adapted to receive from the communicationnetwork 104 the slice support information 116 for at least one slicesupport area of the communication network 104.

Particularly, a network slice can be a logical network that providesspecific network capabilities and network characteristics. A networkslice instance can be a set of network function instances and therequired resources (e.g. compute, storage and networking resources),which form a deployed network slice.

A network function can be a 3rd Generation Partnership Project, 3GPP,defined processing function in a network, which has defined functionalbehaviour and 3GPP defined interfaces. A network function can beimplemented either as a network element on a dedicated hardware, as asoftware instance running on a dedicated hardware, or as a virtualisedfunction instantiated on an appropriate platform, e.g. on a cloudinfrastructure.

The above definitions of network slice, network slice instance andnetwork function are in accordance with the technical specification 3GPPTS 23.501 “System Architecture for the 5G System; Stage 2 (Release 15)”,and for example in the version 1.2.0 dated July 2017 of thespecification 3GPP TS 23.501.

Particularly, a slice support area can comprise at least one cell of thecommunication network. Such a cell generally corresponds to an area ofradio coverage in a cellular communication network. A cell is generallyserved by a base station. A slice support area can be referred to in a5G communication network as a Tracking Area, TA.

Particularly, the registration area can be a Registration Area, RA,according to 5G systems. The user equipment can register with thecommunication network 104 at registration area level, i.e. at aregistration area granularity. As long as the user equipment roamswithin the slice support areas of the registration area it hasregistered, the user equipment does not need to perform a newregistration procedure.

In accordance with the specification 3GPP TR 21.905, for example in itsversion 14.1.1, the registration area can be an area in which the userequipment may roam without a need to perform a new locationregistration. The location registration can be defined as the procedurein which the user equipment registers its presence in a registrationarea, for instance regularly or when entering a new registration area.The location registration can be a Non-Access Stratum, NAS, procedure.

Furthermore, in accordance with the specification 3GPP TS 23.501 v1.2.0,the registration area management can comprise the functions to allocateand reallocate a registration area to a user equipment. Registrationarea can be managed per access type i.e., 3GPP access or Non-3GPPaccess. When the user equipment 102 registers with the communicationnetwork 104 over the 3GPP access, the network entity 114 allocates a setof slice support areas as a registration area to the user equipment.Particularly, the network entity 114 in the form of an Access andMobility Management Function, AMF, can allocate a set of Tracking Areasin TAI List to the user equipment.

When the network entity 114 allocates a registration area to the userequipment, it may take into account various information. Suchinformation may be e.g. the mobility pattern of the user equipment andallowed/non-allowed area. An allowed/non-allowed area can be an area, inwhich the user equipment may or may not initiate communication with thecommunication network 104.

The architecture of the system 100 of FIG. 1 can be based on the 5Gsystem architecture as defined for example in the specification 3GPP TS23.501 v1.2.0. The communication network 104 comprises a Radio AccessNetwork, RAN, 106 and a Core Network, CN, 108. For obtaining serviceconnectivity and e.g. for accessing a service corresponding to a networkslice in the 5G communication system, the UE attaches to the CN 108through the RAN 106.

The Core Network 108 comprises a Control Plane, CP, 110 and User Plane,UP, 112. Separating the UP functions from the CP functions allows forexample independent scalability, evolution and flexible deployments ofthe corresponding functions.

The Control Plane 110 comprises an Access and Mobility ManagementFunction (AMF) or Core Access and Mobility Management Function, whichcan be implemented by the network entity 114. As shown in FIG. 1, thenetwork entity 114 and the user equipment 102 are connected by aconnection N1. The connection N1 is preferably a signalling connection,particularly adapted to transmit Non Access Stratum, NAS, signalling.The network entity is adapted to establish the connection N1 with theuser equipment, and transmit a message comprising the slice supportinformation 116 to the mobile terminal over the connection N1.

The Control Plane 110 can comprise further functions known from 5Gsystems like:

-   -   Network Slice Selection Function (NSSF)    -   Network Exposure Function (NEF)    -   Network Repository Function (NRF)    -   Policy Control function (PCF)    -   Unified Data Management (UDM)    -   Application Function (AF)    -   Authentication Server Function (AUSF)    -   Session Management Function (SMF).

These functions present corresponding service-based interfaces. Forexample and as shown in FIG. 1, the NSSF presents an Nnssf.

The User Plane 112 comprises a User plane Function, UPF, and a Datanetwork, DN, corresponding e.g. to operator services, Internet access or3rd party services.

Particularly, the network entity 114 is adapted to allocate aregistration area to the user equipment 102 for the registration of theuser equipment 102 with the communication network 104. The networkentity 114 is further adapted to transmit, to the user equipment 102,slice support information 116 for all of the slice support areas of theregistration area.

Alternatively, the network entity 114 is further adapted to transmit, tothe user equipment 102, slice support information 116 for a part of allthe slice support of the registration area. This alternative relates toa case in which only partial slice support information is included inthe transmission to the user equipment. The partial slice supportinformation relates to slice support information for certain, but notall, slice support areas of the registration area. For example, theslice support information can indicate supported and/or non-supportednetwork slices of one slice support area. For example, the slice supportinformation of one registration area 200 (per slice support area) can beupdated partially: e.g., the transmitted slice support information canonly include the slice support area(s) and the correspondingsupported/not-supported network slices that are different from what wassignalled to the user equipment in a previously transmitted slicesupport information.

The transmission of partial slice support information can be performed,for example, if the support of network slices has changed in one or moreslice support areas of the registration areas. In such a case, thenetwork entity 114 is allowed to transmit slice support information onlyfor these one or more slice support areas whose network slice supporthas changed. Particularly, the slice support information can indicateone or more additional network slices that are newly supported by agiven slice support area. Furthermore, the slice support information canindicate one or more network slices that are not anymore supported by agiven slice support area.

The slice support information transmitted for a given slice support areacan indicate all network slices that are supported by the given slicesupport area. Alternatively, the slice support information transmittedby the network entity 114 to the user equipment 102 can be related tothe user equipment. In other words, the transmitted slice supportinformation can indicate only the network slices that can be used by theuser equipment. Accordingly, the network entity can analyse whichnetwork slices can be used by the user equipment—for example byreceiving corresponding information from the user equipment or byreading corresponding information stored in the communicationnetwork—and then limit the transmitted slice support information to thenetwork slices that can be used by the user equipment.

FIG. 2 shows slice support information 216 according to an embodiment ofthe present invention.

In this embodiment, a network slice is identified by a Single NetworkSlice Selection Assistance information, S-NSSAI 206. The slice supportinformation 216 for a given slice support area comprises the S-NSSAI 206of at least one network slice that is supported or that is not supportedby the given slice support area. Particularly, it can comprise theS-NSSAI 206 of all network slices that are supported by the given slicesupport area or, alternatively, it can comprise the S-NSSAI 206 of allnetwork slices that are not supported by the given slice support area.

According to the specification 3GPP TS 23.501 v1.2.0, an S-NSSAI 206 cancomprise a Slice/Service type, SST, which refers to the expected networkslice behaviour in terms of features and services. Optionally, theS-NSSAI 206 can also comprise a Slice Differentiator, SD, 210 whichcomplements the Slice/Service type(s) to differentiate amongst multiplenetwork slices of the same Slice/Service type.

The Network Slice Selection Assistance information, NSSAI, is acollection of S-NSSAIs. There can be for example at most 8 S-NSSAIs inthe NSSAI sent in signalling messages between the user equipment 102 andthe communication network 104. Each S-NSSAI assists the communicationnetwork in selecting a particular network slice instance.

In the embodiment of FIG. 2, a slice support area is preferably in theform of a tracking area, and the slice support area is identified by aTracking Area identity, TAI, 204. The registration area 200 is definedby a TAI list 22. The TAI list 202 comprises the TAI 204 of all slicesupport areas comprised in the registration area 200.

In this embodiment, the slice support information can be transmitted bythe network entity 114 for each slice support area of the registrationarea 200, each slice support area being identified by its TAI 204.Alternatively, the slice support information can be transmitted by thenetwork entity 114 for only a part of the slice support areas of theregistration area 200.

In the embodiment of a network entity 114 transmitting to the userequipment 102 slice support information 116 for at least one slicesupport area that is not comprised in the registration area 200, thenthe slice support area can be identified by a TAI. Furthermore, theslice support information 116 for a given slice support area identifiedby a TAI can comprise the S-NSSAI of at least one network slice that issupported or not supported by the given slice support area.

The embodiment of a network entity 114 transmitting to the userequipment 102 slice support information 116 for at least one slicesupport area that is neighbouring a slice support area of theregistration area 200 is similar. The slice support area can beidentified by a TAI. Furthermore, the slice support information 116 fora given slice support area identified by a TAI can comprise the S-NSSAIof at least one network slice that is supported or not supported by thegiven slice support area.

FIG. 3 shows a scenario with different slice supports according to anembodiment of the present invention. Particularly, FIG. 3 shows a firstand a second slice support area of the communication network. The twoslice support areas can be in the form of tracking areas TA1, TA2.

The second slice support area TA2 is comprised within the first slicesupport area TA1. In other words, the radio coverage of the second slicesupport area TA2 is within the radio coverage of the first slice supportarea TA1. In such a scenario the second slice support area TA2 can forexample provide more network slices than the first slice support areaTA1. In the embodiment of FIG. 3, the second slice support area TA2provides two network slices NS1, NS2, while the first slice support areaTA1 provides only network slice NS1.

In case the user equipment profile allows for the connection to bothnetwork slices NS1, NS2, the transmission of the slice supportinformation 116 for both slice support areas TA1, TA2 can beadvantageous. For example, such a transmission can be advantageousparticularly if the registration area 200 is defined as comprising thefirst and second slice support areas TA1, TA2.

On the one hand, in the scenario illustrated by arrow B in FIG. 3, theuser equipment enters the registration area at a location where it caninitiate network slices of the first or second slice support area TA1,TA2. In case the user equipment only needs the network slice NS1, it canadvantageously initiate the network slice NS1 via the first slicesupport area TA1. Since the radio coverage of the first slice supportarea TA1 is larger than the radio coverage of the second slice supportarea TA2, the signalling overhead can be kept low. Indeed, if the userequipment would initiate the network slice NS1 via the second slicesupport area TA2, then additional signalling would be necessary when theuser equipment leaves the second slice support area TA2 and enters thefirst slice support area TA1.

On the other hand, in the scenario illustrated by arrow A in FIG. 3, theuser equipment enters the registration area at a location where it caninitiate network slices of only the first slice support area TA1. Thereception by the user equipment of slice support information regardingboth slice support areas TA1, TA2 is advantageous in this scenario.Indeed, if the user equipment needs the network slice NS2, it caninitiate the network slice NS2 via the second slice support area TA2 assoon as it enters the radio coverage of the second slice support areaTA2.

Particularly, the network entity 114 can be adapted to transmit theslice support information 116 and registration area information in amessage to the user equipment 102. The registration area informationindicates the one or plurality of slice support areas comprised in theregistration area.

FIG. 4 shows a transmission of slice support information during aregistration procedure 400 according to an embodiment of the presentinvention. Particularly, FIG. 4 shows an embodiment for implementing thetransmission of slice support information in the registration procedure.Such a registration procedure is in accordance with 5G systems, forexample in accordance with the specification 3GPP TS 23.502 v0.6.0.

The user equipment needs to register with the communication network toget authorized to receive services so as to enable mobility tracking andreachability. The registration procedure can be used in different usecases:

-   -   during the initial user equipment registration to the 5G system,    -   as a mobility registration update when the user equipment moves        to a new slice area support or tracking area that is located        outside of the registration area 200 of the user equipment, the        user equipment being for example in idle state,    -   as a periodic registration update, and/or    -   when the user equipment needs to update its capabilities or        protocol parameters.

FIG. 4 comprises a user equipment 402, a RAN 406, a network entity 414and slice support information 416, which respectively correspond to theuser equipment 102, RAN 106, network entity 114 and slice supportinformation 116 of FIG. 1.

In step 1, the user equipment 402 sends a Registration Request to theRAN 406. This request can comprise information about a network slicethat the user equipment 402 wants to initiate and/or information aboutnetwork slice(s) that the user equipment 402 can or is authorized touse.

After the RAN 406 has selected the network entity 414 in step 2, the RAN406 forwards the Registration Request to the network entity 414 in step3. The network entity 414 preferably corresponds to the AMF of 5Gsystems.

Further steps are then carried out in the communication network forperforming the registration of the user equipment 402. These steps arereferred to in FIG. 4 as steps 4 to 20 and involve preferably the PCF,SMF, AUSF, UDM as well as a previous network entity referred to as OldAMF in FIG. 4.

In step 21, the network entity 414 transmits to the user equipment 402 aRegistration Accept message to indicate that the registration has beenaccepted by the communication network. The Registration Accept messagecomprises the slice support information 416. The slice supportinformation 416 is preferably transmitted in the Registration Acceptmessage as a separate or additional Information Element, IE.

Preferably this Registration Accept message also includes theregistration area 200 for example in the form of the TAI list 204.

The Registration Accept message can indicate one or more establishedProtocol Data Unit, PDU, sessions to the user equipment in a PDU sessionstatus. The user equipment can remove locally any internal resourcesrelated to PDU sessions that are not marked as established in thereceived PDU session status.

The Registration Accept message can comprise an indication of allowednetwork slices, i.e. an indication of network slices that are allowed bythe communication network. This indication of allowed network slices canbe in the form of corresponding S-NSSAIs.

Optionally, the user equipment can transmit in step 22 a RegistrationComplete message to the network entity 414 to acknowledge theregistration and/or to acknowledge the reception of the slice supportinformation 416.

FIG. 5 shows a transmission of slice support information during a userequipment configuration update procedure according to an embodiment ofthe present invention. Particularly, FIG. 5 shows an embodiment forimplementing the transmission of slice support information in the userequipment configuration update procedure. Such a user equipmentconfiguration update procedure is in accordance with 5G systems, forexample in accordance with the specification 3GPP TS 23.502 v0.6.0.

FIG. 5 comprises a user equipment 502, a RAN 506, a network entity 514preferably in the form of an AMF and slice support information 516,which respectively correspond to the user equipment 102, RAN 106, slicesupport area 114 and slice support information 116 of FIG. 1.

The user equipment configuration update procedure 500, UE ConfigurationUpdate procedure, is used when the network entity 514 wants to changethe user equipment configuration or wants to trigger a user equipmentregistration update procedure.

In a step 1, the network entity 514 sends a user equipment configurationupdate command, UE Configuration Update command, to the user equipment.The UE Configuration Update command comprises the slice supportinformation 516. Preferably, the UE Configuration Update command cancarry the new or updated registration area 200 for the user equipment502, and the related slice support information 516. The slice supportinformation 516 is preferably transmitted in the UE Configuration Updatecommand as a separate or additional Information Element, IE.

FIG. 5 shows the example of UE configuration Update procedure withacknowledgement. The acknowledgement is sent by the user equipment instep 2 to acknowledge the completion of the procedure and/or toacknowledge the reception of the slice support information 516. Theacknowledgment step 2 is optional.

The Registration Accept message of FIG. 4 and the UE ConfigurationUpdate command of FIG. 5 are examples of NAS signalling comprising theslice support information 416, 516. Alternatively, the slice supportinformation 116 can be transmitted by means of other messages or NASsignalling over the connection N1 between network entity and userequipment. Particularly, other NAS procedures can also be used to piggyback the slice support information 116 to the user equipment.

Preferably, the communication network 104 can allocate a registrationarea 200 to the user equipment according to two types of allocation orassignment. The first allocation type consists in allocating aregistration area with different slice support within the registrationarea. In other words, it is possible that the slice support areas of theregistration area have different supported network slices. The secondallocation type consists in allocating a registration area with theconstraints that the network slice support should be the same in allslice support areas of the registration area.

Depending on the user equipment capability, the first allocation type orthe second allocation type can be used. If the user equipment is capableof recognizing the slice support of the network at the current location(e.g. by some network assistance), the first allocation can be used.Otherwise, the second allocation can be used.

Preferably, the transmission of slice support information 116 isperformed by means of an extended NAS signalling over the N1 interface,e.g. by means of a message exchanged during the registration procedureor the user equipment configuration update procedure. The relatedmessage can comprise an extended registration area IE, which can includethe supported network slices S-NSSAI(s) for each slice support area inthe registration area.

The user equipment is able to derive the slice availability in givenslice support area(s) by reading the slice support information that istransmitted for the given slice support area(s). This can be done forexample by receiving the enhanced NAS signalling and reading the TAIlist 202 of the registration area 200 as well as the slice supportinformation 216 for each element of the TAI list 202.

Particularly, when transmitting the slice support information 116, it ispossible to improve the slice support awareness of the user equipmentwithin the registration area. The user equipment can receive a list ofnetwork slices that are supported (e.g. list of S-NSSAI 206). Thenetwork can send the registration area information (e.g. the TAI list202) to the user equipment together with the supported S-NSSAI(s) 206 ofeach slice support area in the TAI list (e.g. during the registrationprocedure). The user equipment can store locally the TAI list 202 andthe supported S-NSSAI(s) 206 of each slice support area in the TAI list202.

When crossing the boundary of slice support areas in the registrationarea, the user equipment intercepts the TAI 204 of the current slicesupport area from the RAN (e.g. by intercepting system information froma radio broadcast channel). The user equipment checks the stored TAIlist 202, and knows the supported slices in the current slice supportarea. Such slice support information can be used by the user equipmentto decide which network slice shall be used to initiate a servicerequest. For example, it is possible to map the service request to asupported network slice that is not the default/optimal one for thatservice. For example, it is also possible for the user equipment tounderstand that it can request a network slice that was not supported bythe previous slice support area.

Particularly, it is possible to optimize the registration areaallocation or assignment strategy. For example, it is possible to assigna registration area to the user equipment in idle mode/state by takinginto account the unified slice support for the slice(s) most probably tobe used. For example, it is possible to assign a registration area tothe user equipment in active mode/state by taking into account theunified support for the slice(s) of active PDU session(s) andpotentially also the other slice(s) most probably to be used.Preferably, only the availability of the slice(s) described above (inidle/active state) should be considered when the network decides on theregistration area of a user equipment.

While the invention has been illustrated and described in detail in thedrawings and the foregoing description, such illustration anddescription are to be considered illustrative or exemplary and notrestrictive. The invention is not limited to the disclosed embodiments.From reading the present disclosure, other modifications will beapparent to a person skilled in the art. Such modifications may involveother features, which are already known in the art and may be usedinstead of or in addition to features already described herein.

The invention has been described in conjunction with various embodimentsherein. However, other variations to the disclosed embodiments can beunderstood and effected by those skilled in the art in practicing theclaimed invention, from a study of the drawings, the disclosure and theappended claims. In the claims, the word “comprising” does not excludeother elements or steps, and the indefinite article “a” or “an” does notexclude a plurality. A single processor or other unit may fulfil thefunctions of several items recited in the claims. The mere fact thatcertain measures are recited in mutually different dependent claims doesnot indicate that a combination of these measures cannot be used toadvantage. A computer program may be stored/distributed on a suitablemedium, such as an optical storage medium or a solid-state mediumsupplied together with or as part of other hardware, but may also bedistributed in other forms, such as via the Internet or other wired orwireless telecommunication systems.

Although the present invention has been described with reference tospecific features and embodiments thereof, it is evident that variousmodifications and combinations can be made thereto without departingfrom the spirit and scope of the invention. The specification anddrawings are, accordingly, to be regarded simply as an illustration ofthe invention as defined by the appended claims, and are contemplated tocover any and all modifications, variations, combinations or equivalentsthat fall within the scope of the present invention.

1. A communication apparatus comprising: at least one processor; and anon-transitory computer-readable storage medium coupled to the at leastone processor and storing programming instructions for execution by theat least one processor, the programming instructions instruct the atleast one processor to perform operations comprising: ascertaining aregistration area allocated to the UE, determining at least one slicesupport area included in the registration area, and transmitting, to theUE, respective slice support information for at least one given slicesupport area of the determined at least one slice support area, therespective slice support information for the at least one given slicesupport area indicating at least one network slice supported by the atleast one given slice support area and/or at least one network slice notsupported by the at least one given slice support area, wherein eachrespective slice support area of the determined slice support areacomprises at least one cell, and wherein each cell of each respectiveslice support area of the determined slice support area supports thesame network slices.